Tag Archives: chemistry

Molecules (arynes) seen for first time in 113 years

Arynes were first theorized in 1902 and they’ve been used as building blocks to synthesize a variety of compounds but they’re existence hasn’t been confirmed until now.

AFM image of an aryne molecule imaged with a CO tip. Courtesy: IBM

AFM image of an aryne molecule imaged with a CO tip. Courtesy: IBM

A July 13, 2015 news item in Nanowerk makes the announcement (Note: A link has been removed),

chemistry teachers and students can breath a sigh of relief. After teaching and learning about a particular family of molecules for decades, scientists have finally proven that they do in fact exist.

In a new paper published online today in Nature Chemistry (“On-surface generation and imaging of arynes by atomic force microscopy”), scientists from IBM Research and CIQUS at the University of Santiago de Compostela, Spain, have confirmed the existence and characterized the structure of arynes, a family of highly-reactive short-lived molecules which was first suggested 113 years ago. The technique has broad applications for on-surface chemistry and electronics, including the preparation of graphene nanoribbons and novel single-molecule devices.

A July 13, 2015 IBM news release by Chris Sciacca, which originated the news item, describes arynes and the imaging process used to capture them for the first time (Note: Links have been removed),

“Arynes are discussed in almost every undergraduate course on organic chemistry around the world. Therefore, it’s kind of a relief to find the final confirmation that these molecules truly exist,” said Prof. Diego Peña, a chemist at the University of Santiago de Compostela.

“I look forward to seeing new chemical challenges solved by the combination of organic synthesis and atomic force microscopy.”

There are trillions of molecules in the universe and some of them are stable enough to be isolated and characterized, but many others are so short-lived that they can only be proposed indirectly, via chemical reactions or spectroscopic methods.

One such species are arynes, which were first suggested in 1902, and since then have been used as intermediates or building blocks in the synthesis of a variety of compounds for applications including medicine, organic electronics and molecular materials. The challenge with these particular molecules is that they only exist for several milliseconds making them extremely challenging to image, until now.

The imaging was accomplished by means of atomic force microscopy (AFM), a scanning technique that can accomplish nanometer-level resolution. After the preparation of the key aryne precursor by CIQUS, IBM scientists used the sharp tip of a scanning tunneling microscope (STM) to generate individual aryne molecules from precursor molecules by atomic manipulation. The experiments were performed on films of sodium chloride, at temperatures near absolute zero, to stabilize the aryne.

Once the molecules were isolated, the team used AFM to measure the tiny forces between the STM tip, which is terminated with a single carbon monoxide molecule, and the sample to image the aryne’s molecular structure. The resulting image was so clear that the scientists could study their chemical nature based on the minute differences between individual bonds.

“Our team has developed several state-of-the-art techniques since 2009, which made this achievement possible,” said Dr. Niko Pavliček, a physicist at IBM Research – Zurich and lead author of the paper. “For this study, it was absolutely essential to pick an insulating film on which the molecules were adsorbed and to deliberately choose the atomic tip-terminations to probe them. We hope this technique will have profound effects on the future of chemistry and electronics.”

Prof. Peña, added that “These findings on arynes can be compared with the long-standing search for the giant squid. For centuries, fishermen had found clues of the existence of this legendary animal. But it was only very recently that scientists managed to film a giant squid alive. In both cases, state-of-the-art technologies were crucial to observe these elusive species alive: a low-noise submarine for the giant squid; a low-temperature AFM for the aryne.”

This research is part of IBM’s five-year, $3 billion investment to push the limits of chip technology and semiconductor innovations needed to meet the emerging demands of cloud computing and Big Data systems.

This work is a result of the large European project called (Planar Atomic and Molecular Scale Devices). PAMS’ main objective is to develop and investigate novel electronic devices of nanometric-scale size. Part of this research is also funded by a European Research Council Advanced Grant awarded to IBM scientist Gerhard Meyer, who is also a co-author of the paper.

Here’s a link to and a citation for the paper,

On-surface generation and imaging of arynes by atomic force microscopy by Niko Pavliček, Bruno Schuler, Sara Collazos, Nikolaj Moll, Dolores Pérez, Enrique Guitián, Gerhard Meyer, Diego Peña, & Leo Gross. Nature Chemistry (2015) doi:10.1038/nchem.2300 Published online 13 July 2015

This paper is behind a paywall.

The science of the Avengers: Age of Ultron

The American Chemical Society (ACS) has produced a video (almost 4 mins.) in their Reactions Science Video Series of podcasts focusing on the Avengers, super heroes, as portrayed in Avengers: Age of Ultron and science. From an April 29, 2015 ACS news release on EurekAlert,

Science fans, assemble! On May 1, the world’s top superhero team is back to save the day in “Avengers: Age of Ultron.” This week, Reactions looks at the chemistry behind these iconic heroes’ gear and superpowers, including Tony Stark’s suit, Captain America’s shield and more.

Here’s the video,

While the chemists are interested in the metal alloys, there is more ‘super hero science’ writing out there. Given my interests, I found the ‘Captain America’s shield as supercapacitor theory’ as described in Matt Shipman’s April 15, 2014 post on The Abstract (North Carolina State University’s official newsroom blog quite interesting. I featured Shipman’s ‘super hero and science’ series of posts in my April 28, 2014 posting.

Gold atoms: sometimes they’re a metal and sometimes they’re a molecule

Fascinating work out of Finland shows that a minor change in the number of gold atoms in your gold nanoparticle can mean the difference between a metal and a molecule (coincidentally, this phenomenon is alluded to in my April 14, 2015 post (Nature’s patterns reflected in gold nanoparticles); more about that at the end of this piece. Getting back to Finland and when gold is metal and when it’s a molecule, here’s more from an April 10, 2015 news item on ScienceDaily,

Researchers at the Nanoscience Center at the University of Jyväskylä, Finland, have shown that dramatic changes in the electronic properties of nanometre-sized chunks of gold occur in well-defined size range. Small gold nanoclusters could be used, for instance, in short-term storage of energy or electric charge in the field of molecular electronics. Funded by the Academy of Finland, the researchers have been able to obtain new information which is important, among other things, in developing bioimaging and sensing based on metal-like clusters.

An April 10, 2015 news release (also on EurekAlert) on the Academy of Finland (Suomen Akatemia) website, which originated the news item, describes the work in more detail,

Two recent papers by the researchers at Jyväskylä (1, 2) demonstrate that the electronic properties of two different but still quite similar gold nanoclusters can be drastically different. The clusters were synthesised by chemical methods incorporating a stabilising ligand layer on their surface. The researchers found that the smaller cluster, with up to 102 gold atoms, behaves like a giant molecule while the larger one, with at least 144 gold atoms, already behaves, in principle, like a macroscopic chunk of metal, but in nanosize.

The fundamentally different behaviour of these two differently sized gold nanoclusters was demonstrated by shining a laser light onto solution samples containing the clusters and by monitoring how energy dissipates from the clusters into the surrounding solvent.

“Molecules behave drastically different from metals,” said Professor Mika Pettersson, the principal investigator of the team conducting the experiments. “The additional energy from light, absorbed by the metal-like clusters, transfers to the environment extremely rapidly, in about one hundred billionth of a second, while a molecule-like cluster is excited to a higher energy state and dissipates the energy into the environment with a rate that is at least 100 times slower. This is exactly what we saw: the 102-gold atom cluster is a giant molecule showing even a transient magnetic state while the 144-gold atom cluster is already a metal. We’ve thus managed to bracket an important size region where this fundamentally interesting change in the behaviour takes place.”

“These experimental results go together very well with what our team has seen from computational simulations on these systems,” said Professor Hannu Häkkinen, a co-author of the studies and the scientific director of the nanoscience centre. “My team predicted this kind of behaviour back in 2008-2009 when we saw big differences in the electronic structure of exactly these nanoclusters. It’s wonderful that robust spectroscopic experiments have now proved these phenomena. In fact, the metal-like 144-atom cluster is even more interesting, since we just published a theoretical paper where we saw a big enhancement of the metallic properties of just a few copper atoms mixed with gold.” (3)

Here are links to and citation for the papers,

Ultrafast Electronic Relaxation and Vibrational Cooling Dynamics of Au144(SC2H4Ph)60 Nanocluster Probed by Transient Mid-IR Spectroscopy by Satu Mustalahti, Pasi Myllyperkiö, Tanja Lahtinen, Kirsi Salorinne, Sami Malola, Jaakko Koivisto, Hannu Häkkinen, and Mika Pettersson. J. Phys. Chem. C, 2014, 118 (31), pp 18233–18239 DOI: 10.1021/jp505464z Publication Date (Web): July 3, 2014

Copyright © 2014 American Chemical Society

Copper Induces a Core Plasmon in Intermetallic Au(144,145)–xCux(SR)60 Nanoclusters by Sami Malola, Michael J. Hartmann, and Hannu Häkkinen. J. Phys. Chem. Lett., 2015, 6 (3), pp 515–520 DOI: 10.1021/jz502637b Publication Date (Web): January 22, 2015

Copyright © 2015 American Chemical Society

Molecule-like Photodynamics of Au102(pMBA)44 Nanocluster by Satu Mustalahti, Pasi Myllyperkiö, Sami Malola, Tanja Lahtinen, Kirsi Salorinne, Jaakko Koivisto, Hannu Häkkinen, and Mika Pettersson. ACS Nano, 2015, 9 (3), pp 2328–2335 DOI: 10.1021/nn506711a Publication Date (Web): February 22, 2015

Copyright © 2015 American Chemical Society

These papers are behind paywalls.

As for my April 14, 2015 post (Nature’s patterns reflected in gold nanoparticles), researchers at Carnegie Mellon University were researching patterns in different sized gold nanoparticles when this was noted in passing,

… Normally, gold is one of the best conductors of electrical current, but the size of Au133 is so small that the particle hasn’t yet become metallic. …

Beginner’s guide to gold nanoparticles in an Academic Minute

Catherine J Murphy, professor of chemistry at the University of Illinois at Urbana-Champaign (UIUC), contributed to Inside Higher Education’s Academic Minute audio podcast series according to an April 9, 2015 news item on the organization’s website.

Murphy provides a very good beginner’s description of gold nanoparticles.

Inside Higher Education offers a transcript of the ‘minute’ by Matthew on its Academic Minute website’s Catherine Murphy webpage,

Introduction: Atomic element #79 is the precious metal more commonly known as gold.

Transcript: Nanotechnology is the study of matter on the 1-100 nanometer scale – about ten to a thousand atoms across. Many elements in the periodic table are metals, and chemists like me are figuring out ways to create tiny metal nanoparticles of different shapes and sizes – spheres, cylinders, stars, you name it. We focus on gold. The cool thing is that each shape and size of gold nanoparticle absorbs and scatters light at different wavelengths, so each size and shape has a different color. So all the colors of the rainbow, and then some, are possible with gold nanoparticles.

The reasons for these neat colors go back to understanding the fundamental nature of light. We know from Maxwell’s equations that light is an electromagnetic wave. If light impinges on a “small conducting sphere,” then there are conditions under which certain wavelengths of light lead to huge oscillations in the electron cloud around the metal, for any metal in the periodic table, as a function of the size of the sphere, the dielectric constant of the metal, and the refractive index of the medium. These equations were worked out by Gustav Mie in the early 1900’s and give us a fundamental understanding of where these brilliant colors come from. In the last 30 years, scientists have adapted his equation for all kinds of shapes beyond spheres.

But gold nanoparticles are not just pretty to look at: they can do a lot of interesting things. For instance, these gold nanoparticles also scatter light, making them easy to find in a simple optical microscope; and since gold is environmentally benign compared to other metals, people are using gold nanoparticles to image biological systems. When you shine light on gold, the absorption of light is very strong at the right wavelengths. Once the particles have absorbed all this energy, what do they do with it? They dump it out as heat to the environment, and so can raise the temperature of their surroundings by many degrees. This is the basis for what scientists call “photothermal therapy,” the idea that if you could target gold nanoparticles to cancer cells, or pathogens, then you could shine light at the wavelength you desire and kill the cancer cells or pathogens. Finally, if you make gold nanoparticles really really small, like 10 atoms across, they no longer act like a noble, unreactive metal at all; they become very active catalysts, like the catalytic converter in your car. So chemists are also very interested in figuring out the transition between unreactive and reactive nanoparticles.

For anyone who might be interested in the series, the Academic Minute covers a wide variety of topics ranging from ‘addiction vaccines’ to ‘digital transgender archives’ to ‘aeroponic gardening’ to ‘a science of the voice’ to ‘Viking social standing’ and more. The series seems to have been started in January 2011 and they’ve been adding to the list of podcasts at a lively rate (lately, it’s one per day). There are over 200 pages of audio podcasts available for your listening pleasure.

The quantum chemistry of nanomedicines

A Jan. 29, 2015 news item on Nanowerk provides an overview of the impact quantum chemical reactions may have on nanomedicines. Intriguingly, this line of query started with computations of white dwarf stars,

Quantum chemical calculations have been used to solve big mysteries in space. Soon the same calculations may be used to produce tomorrow’s cancer drugs.

Some years ago research scientists at the University of Oslo in Norway were able to show that the chemical bonding in the magnetic fields of small, compact stars, so-called white dwarf stars, is different from that on Earth. Their calculations pointed to a completely new bonding mechanism between two hydrogen atoms. The news attracted great attention in the media. The discovery, which in fact was made before astrophysicists themselves observed the first hydrogen molecules in white dwarf stars, was made by UiO’s Centre for Theoretical and Computational Chemistry. They based their work on accurate quantum chemical calculations of what happens when atoms and molecules are exposed to extreme conditions.

A Jan. 29, 2015 University of Oslo press release by Yngve Vogt, which originated the news item, offers a substantive description of molecules, electrons, and more for those of us whose last chemistry class is lost in the mists of time,

The research team is headed by Professor Trygve Helgaker, who for the last thirty years has taken the international lead on the design of a computer system for calculating quantum chemical reactions in molecules.

Quantum chemical calculations are needed to explain what happens to the electrons’ trajectories within a molecule.

Consider what happens when UV radiation sends energy-rich photons into your cells. This increases the energy level of the molecules. The outcome may well be that some of the molecules break up. This is exactly what happens when you sun-bathe.

“The extra energy will affect the behaviour of electrons and can destroy the chemical bonding within the molecule. This can only be explained by quantum chemistry. The quantum chemical models are used to produce a picture of the forces and tensions at play between the atoms and the electrons of a molecule, and of what is required for a molecule to dissociate,” says Trygve Helgaker.

The absurd world of the electrons

The quantum chemical calculations solve the Schrödinger equation for molecules. This equation is fundamental to all chemistry and describes the whereabouts of all electrons within a molecule. But here we need to pay attention, for things are really rather more complicated than that. Your high school physics teacher will have told you that electrons circle the atom. Things are not that simple, though, in the world of quantum physics. Electrons are not only particles, but waves as well. The electrons can be in many places at the same time. It’s impossible to keep track of their position. However, there is hope. Quantum chemical models describe the electrons’ statistical positions. In other words, they can establish the probable location of each electron.

The results of a quantum chemical calculation are often more accurate than what is achievable experimentally.

Among other things, the quantum chemical calculations can be used to predict chemical reactions. This means that the chemists will no longer have to rely on guesstimates in the lab. It is also possible to use quantum chemical calculations in order to understand what happens in experiments.

Enormous calculations

The calculations are very demanding.

“The Schrödinger equation is a highly complicated, partial differential equation, which cannot be accurately solved. Instead, we need to make do with heavy simulations”, says researcher Simen Kvaal.

The computations are so demanding that the scientists use one of the University’s fastest supercomputers.

“We are constantly stretching the boundaries of what is possible. We are restricted by the available machine capacity,” explains Helgaker.

Ten years ago it took two weeks to carry out the calculations for a molecule with 140 atoms. Now it can be done in two minutes.

“That’s 20,000 times faster than ten years ago. The computation process is now running 200 times faster because the computers have been doubling their speed every eighteen months. And the process is a further 100 times faster because the software has been undergoing constant improvement,” says senior engineer Simen Reine.

This year the research group has used 40 million CPU hours, of which twelve million were on the University’s supercomputer, which is fitted with ten thousand parallel processors. This allows ten thousand CPU hours to be over and done with in 60 minutes.

“We will always fill the computer’s free capacity. The higher the computational capacity, the bigger and more reliable the calculations.”

Thanks to ever faster computers, the quantum chemists are able to study ever larger molecules.

Today, it’s routine to carry out a quantum chemical calculation of what happens within a molecule of up to 400 atoms. By using simplified models it is possible to study molecules with several thousand atoms. This does, however, mean that some of the effects within the molecule are not being described in detail.

The researchers are now getting close to a level which enables them to study the quantum mechanics of living cells.

“This is exciting. The molecules of living cells may contain many hundred thousand atoms, but there is no need to describe the entire molecule using quantum mechanical principles. Consequently, we are already at a stage when we can help solve biological problems.”

There’s more from the press release which describes how this work could be applied in the future,

Hunting for the electrons of the insulin molecule

The chemists are thus able to combine sophisticated models with simpler ones. “This will always be a matter of what level of precision and detail you require. The optimal approach would have been to use the Schrödinger equation for everything.”

By way of compromise they can give a detailed description of every electron in some parts of the model, while in other parts they are only looking at average numbers.

Simen Reine has been using the team’s computer program, while working with Aarhus University [Finland], on a study of the insulin molecule. An insulin molecule consists of 782 atoms and 3,500 electrons.

“All electrons repel each other, while at the same time being pulled towards the atomic nuclei. The nuclei also repel each other. Nevertheless, the molecule remains stable. In order to study a molecule to a high level of precision, we therefore need to consider how all of the electrons move relative to one another. Such calculations are referred to as correlated and are very reliable.”

A complete correlated calculation of the insulin molecule takes nearly half a million CPU hours. If they were given the opportunity to run the program on the entire University’s supercomputer, the calculations would theoretically take two days.

“In ten years, we’ll be able to make these calculations in two minutes.”

Medically important

“Quantum chemical calculations can help describe phenomena at a level that may be difficult to access experimentally, but may also provide support for interpreting and planning experiments. Today, the calculations will be put to best use within the fields of molecular biology and biochemistry,” says Knut Fægri [vice-rector at the University of Oslo].

“Quantum chemistry is a fundamental theory which is important for explaining molecular events, which is why it is essential to our understanding of biological systems,” says [Associate Professor] Michele Cascella.

By way of an example, he refers to the analysis of enzymes. Enzymes are molecular catalysts that boost the chemical reactions within our cells.

Cascella also points to nanomedicines, which are drugs tasked with distributing medicine round our bodies in a much more accurate fashion.

“In nanomedicine we need to understand physical phenomena on a nano scale, forming as correct a picture as possible of molecular phenomena. In this context, quantum chemical calculations are important,” explains Michele Cascella.

Proteins and enzymes

Professor K. Kristoffer Andersson at the Department of Biosciences uses the simpler form of quantum chemical calculations to study the details of protein structures and the chemical atomic and electronic functions of enzymes.

“It is important to understand the chemical reaction mechanism, and how enzymes and proteins work. Quantum chemical calculations will teach us more about how proteins go about their tasks, step by step. We can also use the calculations to look at activation energy, i.e. how much energy is required to reach a certain state. It is therefore important to understand the chemical reaction patterns in biological molecules in order to develop new drugs,” says Andersson.

His research will also be useful in the search for cancer drugs. He studies radicals, which may be important to cancer. Among other things, he is looking at the metal ions function in proteins. These are ions with a large number of protons, neutrons and electrons.


Professor Einar Uggerud at the Department of Chemistry has uncovered an entirely new form of chemical bonding through sophisticated experiments and quantum chemical calculations.

Working with research fellow Glenn Miller, Professor Uggerud has found an unusually fragile key molecule, in a kite-shaped structure, consisting of magnesium, carbon and oxygen. The molecule may provide a new understanding of photosynthesis. Photosynthesis, which forms the basis for all life, converts CO2 into sugar molecules.

The molecule reacts so fast with water and other molecules that it has only been possible to study in isolation from other molecules, in a vacuum chamber.

“Time will tell whether the molecule really has an important connection with photosynthesis,” says Einar Uggerud.

I’m delighted with this explanation as it corrects my understanding of chemical bonds and helps me to better understand computational chemistry. Thank you University of Oslo and Yngve Vogt.

Finally, here’s a representation of an insulin molecule as understood by quantum computation,


INSULIN: Working with Aarhus University, Simen Reine has calculated the tensions between the electrons and atoms of an insulin molecule. An insulin molecule consists of 782 atoms and 3,500 electrons. Illustration: Simen Reine-UiO


Licking your way to new ice cream: a physicist’s ice cream changes colour when licked

Bob Yirkas in a July 20, 2014 article for phys.org describes a new twist on ice cream,

Spanish physicist, engineer, professor and ice cream lover Manuel Linares has together with a couple of colleagues created an ice cream that changes colors when it’s licked—in a cone. Not content with the life of a physics professor, Linares signed up for training with Asociación Empresarial Nacional de Elaboradores Artesanos y Comerciantes de Helados y Horchatas—a craftsmen and businessmen association in Spain that offers mentored coursework.

Linares pursued what he has described as a “Masters Diploma in Creating Artisan Ice Cream.” Intrigued by the ice that changes color under fluorescent lights, created by Charlie Francis, Linares set his sights on figuring out a way to create a type of ice cream that would change color in response to temperature changes and acids found in the human mouth. He enlisted the assistance of a couple of unnamed buddies and they all got to work in a lab that Linares put together with his own funds. Linares has told the press that it took the three of them just one week to come up with the color changing ice cream. The final product, which reportedly has a similar taste to tutti-frutti, has been named Xamaleón.

Mariella Moon’s July 30, 2014 article for Engadget reveals more about Linares’ iice cream confection and his future plans,

He [Linares] calls it the Xamaleón, a play on the Spanish word for chameleon, and it originally starts as a periwinkle blue frozen treat until it’s spritzed with Linares’ “love elixir,” a super secret mixture he concocted himself. This mixture reacts to changes in temperature and saliva, causing the tutti-frutti-flavored ice cream to turn into purple, then into pink as you lick.

As unusual as it sounds, this is just the beginning of Linares’ foray into the color-changing ice cream business: he also plans to whip up ice cream that turns from white to pink, and another one that glows under ultraviolet light. You can only get a scoop of this chameleon ice cream from one [of] the creator’s shops in Spain right now, …

The earliest version of this story that I can find is a July 16, 2014 article by Carme Gasull for Cocinatis. You will need Spanish language skills to read it but luckily, this photograph included in the article speaks for itself,

Xamaleón [downloaded from http://www.cocinatis.com/comer/xamaleon-helado-que-cambia-color_2014071600015.html]

Xamaleón [downloaded from http://www.cocinatis.com/comer/xamaleon-helado-que-cambia-color_2014071600015.html]

This is Xamaleón’s pre-love elixir spritz periwinkle blue. You can find more pictures (and a video too) of the ice cream in various stages of its colourful transformation by following this posting’s links to other articles or, if you choose, to search, there’s a lot of material as this has been a very popular topic. BTW, July was National Ice Cream Month as per this July 1, 2014 posting by Anthony Selden for daily.com.

A dog’s intimate understanding of chemical communication: sniffing butts

The American Chemical Society (ACS) has made available a video which answers a question almost everyone has asked at one time or another, why do dogs sniff each other’s bottoms?

Here’s how a July 28, 2014 ACS news release describes this line of inquiry,

Here at Reactions, we ask the tough questions to get to the bottom of the biggest scientific quandaries. In that spirit, this week’s video explains why dogs sniff each other’s butts. It’s a somewhat silly question with a surprisingly complex answer. This behavior is just one of many interesting forms of chemical communication in the animal kingdom

Without more ado, the video,

You can find more videos in ACS’s Reactions series here. (This series was formerly known as Bitesize Science.)

Art (Lawren Harris and the Group of Seven), science (Raman spectroscopic examinations), and other collisions at the 2014 Canadian Chemistry Conference (part 4 of 4)

Cultural heritage and the importance of pigments and databases

Unlike Thom (Ian Thom, curator at the Vancouver Art Gallery), I believe that the testing was important. Knowing the spectra emitted by the pigments in Hurdy Gurdy and Autumn Harbour could help to set benchmarks for establishing the authenticity of the pigments used by artists (Harris and others) in the early part of Canada’s 20th century.

Europeans and Americans are more advanced in their use of technology as a tool in the process of authenticating, restoring, or conserving a piece of art. At the Chicago Institute of Art they identified the red pigment used in a Renoir painting as per my March 24, 2014 posting,

… The first item concerns research by Richard Van Duyne into the nature of the red paint used in one of Renoir’s paintings. A February 14, 2014 news item on Azonano describes some of the art conservation work that Van Duyne’s (nanoish) technology has made possible along with details about this most recent work,

Scientists are using powerful analytical and imaging tools to study artworks from all ages, delving deep below the surface to reveal the process and materials used by some of the world’s greatest artists.

Northwestern University chemist Richard P. Van Duyne, in collaboration with conservation scientists at the Art Institute of Chicago, has been using a scientific method he discovered nearly four decades ago to investigate masterpieces by Pierre-Auguste Renoir, Winslow Homer and Mary Cassatt.

Van Duyne recently identified the chemical components of paint, now partially faded, used by Renoir in his oil painting “Madame Léon Clapisson.” Van Duyne discovered the artist used carmine lake, a brilliant but light-sensitive red pigment, on this colorful canvas. The scientific investigation is the cornerstone of a new exhibition at the Art Institute of Chicago.

There are some similarities between the worlds of science (in this case, chemistry) and art (collectors,  institutions, curators, etc.). They are worlds where one must be very careful.

The scientists/chemists choose their words with precision while offering no certainties. Even the announcement for the discovery (by physicists) of the Higgs Boson is not described in absolute terms as I noted in my July 4, 2012 posting titled: Tears of joy as physicists announce they’re pretty sure they found the Higgs Boson. As the folks from ProsPect Scientific noted,

This is why the science must be tightly coupled with art expertise for an effective analysis.  We cannot do all of that for David [Robertson]. [He] wished to show a match between several pigments to support an interpretation that the ‘same’ paints were used. The availability of Hurdy Gurdy made this plausible because it offered a known benchmark that lessened our dependency on the databases and art-expertise. This is why Raman spectroscopy more often disproves authenticity (through pigment anachronisms). Even if all of the pigments analysed showed the same spectra we don’t know that many different painters didn’t buy the same brand of paint or that some other person didn’t take those same paints and use them for a different painting. Even if all pigments were different, that doesn’t mean Lawren Harris didn’t paint it, it just means different paints were used.

In short they proved that one of the pigments used in Autumn Harbour was also used in the authenticated Harris, Hurdy Gurdy, and the other pigment was in use at that time (early 20th century) in Canada. It doesn’t prove it’s a Harris painting but, unlike the Pollock painting where they found an anachronistic pigment, it doesn’t disprove Robertson’s contention.

To contrast the two worlds, the art world seems to revel in secrecy for its own sake while the world of science (chemistry) will suggest, hint, or hedge but never state certainties. The ProSpect* Scientific representative commented on authentication, art institutions, and databases,

We know that some art institutions are extremely cautious about any claims towards authentication, and they decline to be cited in anything other than the work they directly undertake. (One director of a well known US art institution said to me that they pointedly do not authenticate works, she offered advice on how to conduct the analysis but declined any reference to her institution.) We cannot comment on any of the business plans of any of our customers but the customers we have that use Raman spectroscopy on paintings generally build databases from their collected studies as a vital tool to their own ongoing work collecting and preserving works of art.

We don’t know of anyone with a database particular to pigments used by Canadian artists and neither did David R. We don’t know that any organization is developing such a database.The database we used is a mineral database (as pigments in the early 20th century were pre-synthetic this database contains some of the things commonly used in pigments at that time) There are databases available for many things:  many are for sale, some are protected intellectual property. We don’t have immediate access to a pigments database. Some of our art institution/museum customers are developing their own but often these are not publicly available. Raman spectroscopy is new on the scene relative to other techniques like IR and X-Ray analysis and the databases of Raman spectra are less mature.


Canadian cultural heritage

Whether or not Autumn Harbour is a Lawren Harris painting may turn out to be less important than establishing a means for better authenticating, restoring, and conserving Canadian cultural heritage. (In a June 13, 2014 telephone conversation, David Robertson claims he will forward the summary version of the data from the tests to the Canadian Conservation Institute once it is received.)

If you think about it, Canadians are defined by the arts and by research. While our neighbours to the south went through a revolutionary war to declare independence, Canadians have declared independence through the visual and literary arts and the scientific research and implementation of technology (transportation and communication in the 19th and 20th centuries).

Thank you to both Tony Ma and David Robertson.

Finally, Happy Canada Day on July 1, 2014!

Part 1

Part 2

Part 3

* ‘ProsPect’ changed to ‘ProSpect’ on June 30, 2014.

ETA July 14, 2014 at 1300 hours PDT: There is now an addendum to this series, which features a reply from the Canadian Conservation Institute to a query about art pigments used by Canadian artists and access to a database of information about them.

Lawren Harris (Group of Seven), art authentication, and the Canadian Conservation Insitute (addendum to four-part series)

Art (Lawren Harris and the Group of Seven), science (Raman spectroscopic examinations), and other collisions at the 2014 Canadian Chemistry Conference (part 3 of 4)

Dramatic headlines (again)

Ignoring the results entirely, Metro News Vancouver, which favours the use of the word ‘fraud’, featured it in the headline of a second article about the testing, “Alleged Group of Seven work a fraud: VAG curator” by Thandi Fletcher (June 5, 2014 print issue); happily the online version of Fletcher’s story has had its headline changed to the more accurate: “Alleged Group of Seven painting not an authentic Lawren Harris, says Vancouver Art Gallery curator.” Fletcher’s article was updated after its initial publication with some additional text (it is worth checking out the online version even if you’re already seen the print version). There had been a second Vancouver Metro article on the testing of the authenticated painting by Nick Wells but that in common, with his June 4, 2014 article about the first test, “A fraud or a find?” is no longer available online. Note: Standard mainstream media practice is that the writer with the byline for the article is not usually the author of the article’s headline.

There are two points to be made here. First, Robertson has not attempted to represent ‘Autumn Harbour’ as an authentic Lawren Harris painting other than in a misguided headline for his 2011 news release.  From Robertson’s July 26, 2011 news release (published by Reuters and published by Market Wired) where he crossed a line by stating that Autumn Harbour is a Harris in his headline (to my knowledge the only time he’s done so),

Lost Lawren Harris Found in Bala, Ontario

Unknown 24×36 in. Canvas Piques a Storm of Controversy

VANCOUVER, BRITISH COLUMBIA–(Marketwire – July 26, 2011) –
Was Autumn Harbour painted by Lawren Harris in the fall of 1912? That summer Lawren Harris was 26 years old and had proven himself as an accomplished and professional painter. He had met J.E.H. MacDonald in November of 1911. They became fast friends and would go on to form the Group of Seven in 1920 but now in the summer of 1912 they were off on a sketching expedition to Mattawa and Temiscaming along the Quebec-Ontario border. Harris had seen the wilderness of the northern United States and Europe but this was potentially his first trip outside the confines of an urban Toronto environment into the Canadian wilderness.

By all accounts he was overwhelmed by what he saw and struggled to find new meaning in his talents that would capture these scenes in oil and canvas. There are only two small works credited to this period, archived in the McMichael gallery in Kleinburg, Ontario. Dennis Reid, Assistant Curator of the National Gallery of Canada stated in 1970 about this period: “Both Harris and (J.E.H.) MacDonald explored new approaches to handling of colour and overall design in these canvases. Harris in particular was experimenting with new methods of paint handling, and Jackson pointed out the interest of the other painters in these efforts, referring to the technique affectionately as ‘Tomato Soup’.” For most authorities the summer and fall of 1912 are simply called his ‘lost period’ because it was common for Harris to destroy, abandon or give away works that did not meet his standards. The other trait common to Harris works, is the lack of a signature and some that are signed were signed on his behalf. The most common proxy signatory was Betsy Harris, his second wife who signed canvases on his behalf when he could no longer do so.

So the question remains. Can an unsigned 24×36 in. canvas dated to 1900-1920 that was found in a curio shop in Bala, Ontario be a long lost Lawren Harris? When pictures were shown to Charles C. Hill, Curator of Canadian Art, National Gallery of Canada, he replied: “The canvas looks like no Harris I have ever seen…” A similar reply also came from Ian Thom, Head Curator for the Vancouver Art Gallery: “I do not believe that your work can be connected with Harris in any way.” [emphases mine] Yet the evidence still persists. The best example resides within the National Art Gallery. A 1919, 50.5 X 42.5 in. oil on rough canvas shows Harris’s style of under painting, broad brush strokes and stilled composition. Shacks, painted in 1919 and acquired the Gallery in 1920 is an exact technique clone of Autumn Harbour. For a list of comparisons styles with known Harris works and a full list of the collected evidence please consult www.1912lawrenharris.ca/ and see for yourself.

If Robertson was intent on perpetrating a fraud, why would he include the negative opinions from the curators or attempt to authenticate his purported Harris? The 2011 website is no longer available but Robertson has established another website, http://autumnharbour.ca/.

It’s not a crime (fraud) to have strong or fervent beliefs. After all, Robertson was the person who contacted ProSpect* Scientific to arrange for a test.

Second, Ian Thom, the VAG curator did not call ‘Autumn Harbour’ or David Robertson, a fraud. From the updated  June 5, 2014 article sporting a new headline by Thandi Fletcher,

“I do not believe that the painting … is in fact a Lawren Harris,” said Ian Thom, senior curator at the Vancouver Art Gallery, “It’s that simple.”

It seems Thom feels as strongly as Robertson does; it’s just that Thom holds an opposing opinion.

Monetary value was mentioned earlier as an incentive for Robertson’s drive to prove the authenticity of his painting, from the updated June 5, 2014 article with the new headline by Thandi Fletcher,

Still, Robertson, who has carried out his own research on the painting, said he is convinced the piece is an authentic Harris. If it were, he said it would be worth at least $3 million. [emphasis mine]

“You don’t have to have a signature on the canvas to recognize brushstroke style,” he said.

Note: In a June 13, 2014 telephone conversation, Robertson used the figure of $1M to denote his valuation of Autumn Harbour and claimed a degree in Geography with a minor in Fine Arts from the University of Waterloo. He also expressed the hope that Autumn Harbour would prove to be a* Rosetta Stone of sorts for art pigments used in the early part of the 20th century.

As for the owner of Hurdy Gurdy and the drama that preceded its test on June 4, 2014, Fletcher had this in her updated and newly titled article,

Robertson said the painting’s owner, local Vancouver businessman Tony Ma, had promised to bring the Harris original to the chemistry conference but pulled out after art curator Thom told him not to participate.

While Thom acknowledged that Ma did ask for his advice, he said he didn’t tell him to pull out of the conference.

“It was more along the lines of, ‘If I were you, I wouldn’t do it, because I don’t think it’s going to accomplish anything,’” said Thom, adding that the final decision is up to Ma. [emphasis mine]

A request for comment from Ma was not returned Wednesday [June 5, 2014].

Thom, who already examined Robertson’s painting a year ago [in 2013? then, how is he quoted in a 2011 news release?], said he has no doubt Harris did not paint it.

“The subject matter is wrong, the handling of the paint is wrong, and the type of canvas is wrong,” he said, adding that many other art experts agree with him.

Part 1

Part 2

Part 4

* ‘ProsPect’ changed to ‘ProSpect’ on June 30, 2014. Minor grammatical change made to sentence: ‘He also expressed the hope that Autumn Harbour would prove to a be of Rosetta Stone of sorts for art pigments used in the early part of the 20th century.’ to ‘He also expressed the hope that Autumn Harbour would prove to be a* Rosetta Stone of sorts for art pigments used in the early part of the 20th century.’ on July 2, 2014.

ETA July 14, 2014 at 1300 hours PDT: There is now an addendum to this series, which features a reply from the Canadian Conservation Institute to a query about art pigments used by Canadian artists and access to a database of information about them.

Lawren Harris (Group of Seven), art authentication, and the Canadian Conservation Insitute (addendum to four-part series)

Art (Lawren Harris and the Group of Seven), science (Raman spectroscopic examinations), and other collisions at the 2014 Canadian Chemistry Conference (part 2 of 4)

Testing the sample and Raman fingerprints

The first stage of the June 3, 2010 test of David Robertson’s Autumn Harbour, required taking a tiny sample from the painting,. These samples are usually a fleck of a few microns (millionths of an inch), which can then be tested to ensure the lasers are set at the correct level assuring no danger of damage to the painting. (Robertson extracted the sample himself prior to arriving at the conference. He did not allow anyone else to touch his purported Harris before, during, or after the test.)

Here’s how ProSpect* Scientific describes the ‘rehearsal’ test on the paint chip,

Tests on this chip were done simply to ensure we knew what power levels were safe for use on the painting.  While David R stated he believed the painting was oil on canvas without lacquer, we were not entirely certain of that.  Lacquer tends to be easier to burn than oil pigments and so we wanted to work with this chip just to be entirely certain there was no risk to the painting itself.

The preliminary (rehearsal) test resulted in a line graph that showed the frequencies of the various pigments in the test sample. Titanium dioxide, for example, was detected and its frequency (spectra) reflected on the graph.

I found this example of a line graph representing the spectra (fingerprint) for a molecule of an ultramarine (blue) pigment along with a general explanation of a Raman ‘fingerprint’. There is no indication as to where the ultramarine pigment was obtained. From the  WebExhibits.org website featuring a section on Pigments through the Ages and a webpage on Spectroscopy,


Ultramarine [downloaded from http://www.webexhibits.org/pigments/intro/spectroscopy.html]

Raman spectra consist of sharp bands whose position and height are characteristic of the specific molecule in the sample. Each line of the spectrum corresponds to a specific vibrational mode of the chemical bonds in the molecule. Since each type of molecule has its own Raman spectrum, this can be used to characterize molecular structure and identify chemical compounds.

Most people don’t realize that the chemical signature (spectra) for pigment can change over time with new pigments being introduced. Finding a pigment that was on the market from 1970 onwards in a painting by Jackson Pollock who died in 1956 suggests strongly that the painting couldn’t have come from Pollock’s hand. (See Michael Shnayerson’s May 2012 article, A Question of Provenance, in Vanity Fair for more about the Pollock painting. The article details the fall of a fabled New York art gallery that had been in business prior to the US Civil War.)

The ability to identify a pigment’s molecular fingerprint means that an examination by Raman spectroscopy can be part of an authentication, a restoration, or a conservation process. Here is how a representative from ProSpect Scientific describes the process,

Raman spectroscopy is non-destructive (when conducted at the proper power levels) and identifies the molecular components in the pigments, allowing characterization of the pigments for proper restoration or validation by comparison with other pigments of the same place/time. It is valuable to art institutions and conservators because it can do this.  In most cases of authentication Raman spectroscopy is one of many tools used and not the first in line. A painting would be first viewed by art experts for technique, format etc, then most often analysed with IR or X-Ray, then perhaps Raman spectroscopy. It is impossible to use Raman spectroscopy to prove authenticity as paint pigments are usually not unique to any particular painter.  Most often Raman spectroscopy is used by conservators to determine proper pigments for appropriate restoration.  Sometimes Raman will tell us that the pigment isn’t from the time/era the painting is purported to be from (anachronisms).

Autumn Harbour test

Getting back to the June 3, 2014 tests, once the levels were set then it was time to examine Autumn Harbour itself to determine the spectra for the various pigments.  ProSpect Scientific has provided an explanation of the process,

This spectrometer was equipped with an extension that allowed delivery of the laser and collection of the scattered light at a point other than directly under the microscope. We could also have used a flexible fibre optic probe for this, but this device is slightly more efficient. This allowed us to position the delivery/collection point for the light just above the painting at the spot we wished to test. For this test, we don’t sweep across the surface, we test a small pinpoint that we feel is a pigment of the target colour.

We only use one laser at a time. The system is built so we can easily select one laser or another, depending on what we wish to look at. Some researchers have 3 or 4 lasers in their system because different lasers provide a better/worse raman spectrum depending on the nature of the sample. In this case we principally used the 785nm laser as it is better for samples that exhibit fluorescence at visible wavelengths. 532nm is a visible wavelength.  For samples that didn’t produce good signal we tried the 532nm laser as it produces better signal to noise than 785nm, generally speaking. I believe the usable results in our case were obtained with the 785nm laser.

The graphed Raman spectra shows peaks for the frequency of scattered light that we collect from the laser-illuminated sample (when shining a laser on a sample the vast majority of light is scattered in the same frequency of the laser, but a very small amount is scattered at different frequencies unique to the molecules in the sample). Those frequencies correspond to and identify molecules in the sample. We use a database (on the computer attached to the spectrometer) to pattern match the spectra to identify the constituents.

One would have thought ‘game over’ at this point. According to some informal sources, Canada has a very small (almost nonexistent) data bank of information about pigments used in its important paintings. For example, the federal government’s Canadian Conservation Institute (CCI) has a very small database of pigments and nothing from Lawren Harris paintings [See the CCI’s response in this addendum], so the chances that David Robertson would have been able to find a record of pigments used by Lawren Harris roughly in the same time period that Autumn Harbour seems to have been painted are not good.

Everything changes

In a stunning turn of events and despite the lack of enthusiasm from Vancouver Art Gallery (VAG) curator, Ian Thom, on Wednesday, June 4, 2014 the owner of the authenticated Harris, Hurdy Gurdy, relented and brought the painting in for tests.

Here’s what the folks from ProSpect Scientific had to say about the comparison,

Many pigments were evaluated. Good spectra were obtained for blue and white. The blue pigment matched on both paintings, the white didn’t match. We didn’t get useful Raman spectra from other pigments. We had limited time, with more time we might fine tune and get more data.

One might be tempted to say that the results were 50/50 with one matching and the other not, The response from the representative of ProSpect Scientific is more measured,

We noted that the mineral used in the pigment was the same.  Beyond that is interpretation:  Richard offered the view that lapis-lazuli was a typical and characteristic component for blue in that time period (early 1900’s).   We saw different molecules in the whites used in the two paintings, and Richard offered that both were characteristic of the early 1900’s.

Part 1

Part 3

Part 4

* ‘ProsPect’ changed to ‘ProSpect’ on June 30, 2014.

ETA July 14, 2014 at 1300 hours PDT: There is now an addendum to this series, which features a reply from the Canadian Conservation Institute to a query about art pigments used by Canadian artists and access to a database of information about them.

Lawren Harris (Group of Seven), art authentication, and the Canadian Conservation Insitute (addendum to four-part series)